Some examples of previous efforts to control or estimate the position of a free-space electrical current, such as an electric arc or other electrical discharge, are disclosed in:                U.S. Pat. No. 2,727,936 entitled “Titanium furnace” issued Dec. 20, 1955 to Boyer;        U.S. Pat. No. 2,727,937 entitled “High-vacuum titanium furnace” issued Dec. 20, 1955 to Boyer;        U.S. Pat. No. 2,951,890 entitled “Method of operating an electric arc furnace” issued Sep. 6, 1960 to Yeomans et al;        U.S. Pat. No. 2,972,695 entitled “Stabilisation of low pressure D.C. arc discharges” issued Feb. 21, 1961 to Wroe;        U.S. Pat. No. 2,978,525 entitled “Magnetic field coil for concentrating the arc in a vacuum arc furnace” issued Apr. 4, 1961 to Gruber et al;        U.S. Pat. No. 3,398,229 entitled “Non-consumable arc electrode” issued Aug. 20, 1968 to De Corso;        U.S. Pat. No. 3,546,348 entitled “Non-consumable electrode vacuum arc furnaces for steel, zirconium, titanium and other metals and processes for working said metals” issued Dec. 8, 1970 to De Corso;        U.S. Pat. No. 3,628,948 entitled “Electric arc vacuum remelting processes” issued Dec. 21, 1971 to Bruning;        U.S. Pat. No. 3,680,163 entitled “Non-consumable electrode vacuum arc furnaces for steel, zirconium, titanium and other metals and processes for working said metals” issued Aug. 1, 1972 to De Corso;        U.S. Pat. No. 3,708,279 entitled “Process of refining metal in a vacuum with coaxially mounted non-consumable electrodes” issued Jan. 2, 1973 to De Corso;        U.S. Pat. No. 4,122,292 entitled “Electric arc heating vacuum apparatus” issued Oct. 24, 1978 to Karinsky;        U.S. Pat. No. 4,581,745 entitled “Electric arc melting apparatus and associated method” issued Apr. 8, 1986 to Mathews et al;        U.S. Pat. No. 4,762,165 entitled “Arc melting and casting method and apparatus thereof” issued Aug. 9, 1988 to Ogino et al;        U.S. Pat. No. 5,373,529 entitled “Metals purification by improved vacuum arc remelting” issued Dec. 13, 1994 to Zanner et al;        U.S. Pat. No. 8,111,059 entitled “Electrical current locator” issued Feb. 7, 2012 to King et al;        U.S. Pre-grant Pub. No. 2018/0088164 entitled “Estimation of arc location in three dimensions” published Mar. 29, 2018 in the names of Cibula et al;        JP S60-077939 entitled “Manufacture of ingot by vacuum-arc remelting” published May 2, 1985 in the name of Kobe Steel Ltd;        JP H03-274382 entitled “Vacuum arc melting” published Dec. 5, 1991 in the name of Daido Steel Co Ltd;        Zanner et al; Observations of melt rate as a function of . . . during vacuum consumable arc remelting of . . . ; Metallurgical & Materials Transactions B v15 p117 (1984);        Zanner et al; On the Origin of Defects in VAR Ingots; International Symposium on Liquid Metal Processing and Casting, Santa Fe, N. Mex., USA, p13 (2005);        WARD et al; Ensemble Arc Motion & Solidification During the Vacuum Arc Remelting of a Nickel-based Superalloy; Int'l Symp on Liquid Metal Processing & Casting; p49 (2005);        Woodside; Investigating arc behavior in a DC vacuum arc remelting furnace using magnetic flux density measurements; masters thesis, Oregon State University; (2008);        Woodside; Arc Distribution and Motion During the Vacuum Arc Remelting Process As Detected with a Magnetostatic Approach; PhD dissertation, Oregon State University (2010);        Woodside et al; A Measurement System for Determining the Positions of Arcs During Vacuum Arc Remelting; IEEE Int'l Instrumentation & Measurement Tech Conf; p 452 (2010);        Woodside et al: Characterizing Arc Motion and Distribution During Vacuum Arc Remelting; Int'l Symp on Liquid Metal Processing & Casting; v75 (2009); and        Woodside et al; Arc Distribution During the Vacuum Arc Remelting of Ti-6Al-4V; Metallurgical & Materials Transactions B v44 n1 p154 (2012).        
Each of the preceding patents, applications, and publications is hereby incorporated by reference as if fully set forth herein.